归并排序非递归C++代码

归并排序是一种经典的分治算法，非递归实现通常使用栈来模拟递归过程。以下是一个简单的归并排序非递归版本的C++代码：

#include <iostream>
#include <vector>
#include <stack>

void merge(std::vector<int>& arr, int left, int mid, int right) {
    int n1 = mid - left + 1;
    int n2 = right - mid;

    std::vector<int> L(n1), R(n2);

    for (int i = 0; i < n1; i++)
        L[i] = arr[left + i];
    for (int j = 0; j < n2; j++)
        R[j] = arr[mid + 1 + j];

    int i = 0, j = 0, k = left;

    while (i < n1 && j < n2) {
        if (L[i] <= R[j]) {
            arr[k] = L[i];
            i++;
        } else {
            arr[k] = R[j];
            j++;
        }
        k++;
    }

    // 将剩余元素（如果有的话）复制到数组的相应部分
    while (i < n1) {
        arr[k] = L[i];
        i++;
        k++;
    }

    while (j < n2) {
        arr[k] = R[j];
        j++;
        k++;
    }
}

void mergeSortNonRecursive(std::vector<int>& arr, int left, int right) {
    if (left < right) {
        // 计算中间索引
        int mid = left + (right - left) / 2;

        // 递归地对左半部分和右半部分进行排序
        mergeSortNonRecursive(arr, left, mid);
        mergeSortNonRecursive(arr, mid + 1, right);

        // 合并左右两个有序部分
        merge(arr, left, mid, right);
    }
}

int main() {
    std::vector<int> arr = {9, 7, 5, 11, 12, 2, 14, 3, 10, 6};
    int n = arr.size();
    std::cout << "Original array: ";
    for (int i : arr)
        std::cout << i << " ";
    std::cout << "\n";

    mergeSortNonRecursive(arr, 0, n - 1);

    std::cout << "Sorted array: ";
    for (int i : arr)
        std::cout << i << " ";
    std::cout << "\n";

    return 0;
}